For millions of years, humans evolved under full-spectrum sunlight. Our cells and biology are specifically designed to respond to different wavelengths. Now we spend 16+ hours a day indoors, creating a form of "light malnutrition."

Each wavelength of light speaks to your body in a different language, triggering specific biological responses. It's like having access to dozens of free medicines, but most of us never use them. Here's how each part of the light spectrum impacts your biology:

→ ULTRAVIOLET LIGHT (UVB) Despite what you've been told, small doses of UVB can be remarkably beneficial. When UVB hits your skin, it converts cholesterol into vitamin D, which is vital for bone health and immune modulation. It also prompts your skin to release nitric oxide, which dilates blood vessels and lowers blood pressure.

The key is finding the "therapeutic window." i.e. enough for health benefits, not enough to burn. For most people, this means just 5-15 minutes of midday sun exposure several times per week. NEVER exceed the amount that causes you to burn.

→ BLUE LIGHT (400-490nm) Blue light is a double-edged sword. In the morning, it's a powerful regulator of your circadian rhythm. Blue-rich morning light signals your brain to stop producing melatonin and start producing cortisol, boosting alertness and mood.

But at night? That same blue light becomes your worst enemy. Studies show blue light at night suppresses melatonin for TWICE as long as green light and shifts your body clock by about 3 hours. Even dim room light (8 lux - less than a lamp) can mess with your melatonin.

→ GREEN LIGHT (495-570nm) This is where it gets interesting... Green light is emerging as a powerful therapy for pain and headaches. In one study, migraine sufferers exposed to different colors found that all colors WORSENED headache pain except green.

Green light reduced pain by about 20%. A clinical trial with chronic migraine patients had them spend 1-2 hours daily in a green-lit room. Over 10 weeks, their headache days decreased from 22 to 9 per month - nearly a 60% reduction. Simply wearing green-tinted glasses shows similar benefits, suggesting it works through your eyes, not just your skin.

→ YELLOW/AMBER LIGHT (570-590nm) Yellow light is often overlooked but has exceptional skin benefits. It penetrates the skin to a shallow depth (0.5-2mm) and primarily affects the epidermis.

Yellow light reduces redness and inflammation while boosting circulation and lymphatic drainage. It's shown to increase collagen production and red blood cell formation in the skin, supporting wound healing and tissue repair. If you've ever wondered why you look better in "golden hour" light; this is why.

→ RED LIGHT (620-750nm): Red light (and IR light) are interventions I use often. (15-20mins red light therapy daily) When red light reaches your cells, it's absorbed by mitochondria (your cellular power plants) through an enzyme called cytochrome c oxidase.

This increases ATP production, essentially giving your cells an energy boost. The results? • Faster tissue repair • Increased collagen production • Reduced inflammation • Improved circulation

Red light therapy has been shown to speed healing of wounds, reduce joint pain, and even help regrow hair in some cases of alopecia. For muscle recovery, red light reduces soreness and fatigue by decreasing inflammation and oxidative damage after exercise.

→ INFRARED LIGHT (750nm+) Invisible to the eye but felt as heat, infrared light has profound healing effects. Near-infrared (750-1400nm) penetrates DEEPEST any light, reaching several cm into tissue. This means it can affect muscles, nerves, and even bones to some degree. Mid and far-infrared cause less penetration but trigger whole-body responses through gentle heating.

Now, how do you actually USE this knowledge? Here's my three-tiered approach to optimising your light environment:

TIER 1: FREE LIGHT OPTIMISATION 1. Get morning sunlight within 30-60 minutes of waking. This is non-negotiable. Even on cloudy days, outdoor light far exceeds indoor lamp intensity. Just 5-15 minutes sets your body clock, boosts mood, and improves sleep that night. 2. Take a midday outdoor break. Around solar noon, the sun offers the brightest light and UVB for vitamin D. A brief 10-20 minute walk can top up your vitamin D levels and deliver a hefty dose of illuminance. 3. Practice evening light hygiene. In the hours before bed, dim overhead lights and switch to warm amber lighting. Limit screen use or use blue-light filters on devices. Your goal: create a cave-like environment for sleep. 4. Instal flux on your desktop which adjusts the spectrum of light according to sunrise and sunset.

TIER 2: BUDGET-FRIENDLY LIGHT TOOLS 1. Light therapy lamp (10,000 lux) For those who can't get sufficient sunshine (winter, shift work), a light therapy box is an evidence-based solution. Use for about 30 minutes in the morning to treat seasonal depression and improve mood. 2. Blue-blocking glasses Amber-tinted glasses worn in the evening block the melatonin-disrupting blue light. Studies show people wearing these maintain normal melatonin production even under bright indoor light. Don’t wear blue light blockers during the day (especially the morning). Your body needs this blue light in order to rise. Cost: $10-50 3. Green-tinted migraine glasses If you suffer from headaches or migraines, green-tinted glasses can reduce pain without drugs. 4. Philips Hue Red light bulbs: Switching to red in the evening hours (stimulates melatonin) 5. Switch from bright overhead lights to eye-level warmer bulbs (i.e. lamps). ⁠Remove all white bulbs, shift to a warmer orange tone instead.

TIER 3: ADVANCED LIGHT THERAPY 1. Red light therapy devices From small handheld units to full-body panels, these deliver focused red/near-infrared light. Look for wavelengths around 630-670nm (red) and 810-850nm (near-infrared) for best results. Sessions typically run 5-15 minutes, repeated several times weekly. 2. Infrared saunas Far-infrared saunas use IR lamps to heat your body directly without excessively heating the air. Start at around 43°C (110°F) for 5-10 minutes and gradually increase to 20-30 minute sessions. The key to success with ANY light therapy is consistency. Create a personalised "light diet" based on your specific goals: For MOOD improvement: • Morning sunlight or bright light therapy • Midday outdoor exposure • Red light therapy 3-4x weekly For SLEEP enhancement: • Morning sunlight (critical!) • Amber lighting after sunset • Blue-blocking glasses 2 hours before bed • Complete darkness while sleeping For SKIN health: • Moderate morning sun (with protection if needed) • Red light therapy for collagen production • Yellow light for inflammation/redness For PAIN management: • Green light or green-tinted glasses for headaches • Red/NIR light on joints or muscles for inflammation • Infrared sauna sessions for full-body relief

Your body evolved to thrive under natural light cycles. By understanding these wavelengths and using them strategically, you can unlock healing potential that modern medicine is only beginning to understand.